The disclosure relates generally to distributed antenna systems (DASs) and more particularly to selective activation of communications services during remote unit power-up in a DAS based on power consumption.
Wireless communication is rapidly growing, with ever-increasing demands for high-speed mobile data communication. As an example, local area wireless services (e.g., so-called “wireless fidelity” or “WiFi” systems) and wide area wireless services are being deployed in many different types of areas (e.g., coffee shops, airports, libraries, etc.). Distributed communications or antenna systems communicate with wireless devices called “clients,” “client devices,” or “wireless client devices,” which must reside within the wireless range or “cell coverage area” in order to communicate with an access point device. DASs are particularly useful to be deployed inside buildings or other indoor environments where client devices may not otherwise be able to effectively receive radio frequency (RF) signals from a source, such as a base station for example. Example applications where DASs can be used to provide or enhance coverage for wireless services include public safety, cellular telephony, wireless local access networks (LANs), location tracking, and medical telemetry inside buildings and over campuses.
One approach to deploying a DAS involves the use of RF antenna coverage areas, also referred to as “antenna coverage areas.” Antenna coverage areas can have a radius in the range from a few meters up to twenty meters as an example. One type of DAS for creating antenna coverage areas, called “Radio-over-Fiber” or “RoF,” utilizes RF communications signals sent over optical fibers. Both types of systems can include head-end equipment coupled to a plurality of remote antenna units (RAUs) that each provides antenna coverage areas. The RAUs can each include RF transceivers coupled to an antenna to transmit RF communications signals wirelessly, wherein the RAUs are coupled to the head-end equipment via the communication medium. The RAUs contain power-consuming components, such as the RF transceiver, to transmit and receive RF communications signals and thus require power to operate. Power may be provided to the RAUs from remote power supplies, such as at an intermediate distribution frame (IDF), or interconnect unit (ICU) closet at each floor of the building infrastructure.
In this regard, FIG. 1 is a schematic diagram of an embodiment of a DAS. In this embodiment, the system is an optical fiber-based DAS 10. The DAS 10 is configured to create one or more antenna coverage areas for establishing communications with wireless client devices located in the RF range of the antenna coverage areas. The DAS 10 provides RF communication services (e.g., cellular services). In this embodiment, the DAS 10 includes head-end equipment (HEE) 12 such as a head-end unit (HEU), one or more remote antenna units (RAUs) 14, and an optical fiber 16 that optically couples the HEE 12 to the RAU 14. The RAU 14 is a type of remote communications unit. In general, a remote communications unit can support either wireless communications, wired communications, or both. The RAU 14 can support wireless communications and/or wired communications. The HEE 12 is configured to receive communications over downlink electrical RF signals 18D from a source or sources, such as a network or carrier, and provide such communications to the RAU 14. The HEE 12 is also configured to return communications received from the RAU 14, via uplink electrical RF signals 18U, back to the source. In this regard in this embodiment, the optical fiber 16 includes at least one downlink optical fiber 16D to carry signals communicated from the HEE 12 to the RAU 14 and at least one uplink optical fiber 16U to carry signals communicated from the RAU 14 back to the HEE 12.
The optical fiber-based DAS 10 has an antenna coverage area 20 that can be disposed about the RAU 14. The antenna coverage area 20 of the RAU 14 forms an RF coverage area 21. The HEE 12 is adapted to perform or to facilitate any one of a number of Radio-over-Fiber (RoF) applications, such as RF identification (RFID), wireless local-area network (WLAN) communication, or cellular phone service. Shown within the antenna coverage area 20 is a client device 24 in the form of a cellular telephone. The client device 24 can be any device that is capable of receiving RF communications signals. The client device 24 includes an antenna 26 (e.g., a wireless card) adapted to receive and/or send electromagnetic RF signals. To communicate the electrical RF signals over the downlink optical fiber 16D to the RAU 14, to in turn be communicated to the client device 24 in the antenna coverage area 20 formed by the RAU 14, the HEE 12 includes a radio interface in the form of an electrical-to-optical (E/O) converter 28. The E/O converter 28 converts the downlink electrical RF signals 18D to downlink optical RF signals 22D to be communicated over the downlink optical fiber 16D. The RAU 14 includes an optical-to-electrical (O/E) converter 30 to convert received downlink optical RF signals 22D back to electrical RF signals to be communicated wirelessly through an antenna 32 of the RAU 14 to client devices 24 located in the antenna coverage area 20. Similarly, the antenna 32 is also configured to receive wireless RF communications from client devices 24 in the antenna coverage area 20. In this regard, the antenna 32 receives wireless RF communications from client devices 24 and communicates electrical RF signals representing the wireless RF communications to an E/O converter 34 in the RAU 14. The E/O converter 34 converts the electrical RF signals into uplink optical RF signals 22U to be communicated over the uplink optical fiber 16U. An O/E converter 36 provided in the HEE 12 converts the uplink optical RF signals 22U into uplink electrical RF signals, which can then be communicated as uplink electrical RF signals 18U back to a network or other source.
In the DAS 10 in FIG. 1, the RAUs 14 are powered from a centralized power supply 38 in the HEE 12 through electrical conductors 40. The electrical conductors 40 may be provided in hybrid cables along with the downlink optical fiber 16D. The power is limited to specified power levels by regulations and/or by the power supply's capabilities. The power may be used to power several services at the RAU 14. However circumstances might arise in which the total power required for the operation of all services might exceed the maximum power level that the centralized power supply is allowed to provide. This situation might arise due to an increase in the power consumed by a communications service, such as due to a normal variation from the nominal power of the service or a failure in a service. Reduction in the ability of the system infrastructure to provide power, such as by high cable losses or improper settings for the power supply, can also cause the available power to exceed maximum power levels.
If a RAU 14 in the DAS 10 attempts to draw power in excess of the allowed power, the power supply 38 can shut down thereby shutting down operation of the RAU 14 and its communications services. The power supply 38 may renew power only after the power consumption goes below the maximum allowable power. This condition might require replacement of cabling or the RAU 14.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.